1. Field of the Invention
This invention relates generally to railway cars and in particular to a shear resistant roll restraining means for a freight car.
2. Description of the Prior Art
During rail use of a railway car having a car body including transverse car body bolsters pivotally coupled and supported on transverse truck bolsters, discontinuieties in the track surface, truck hunting and the inertia of the car will cause the car body and therefore the car body bolsters to rock or roll relative to the truck bolsters. If this motion is not restrained or substantially arrested, the rocking motion will cause excessive wear and fatigue fracture of the center plate and bowl pivotally coupling the truck and car body bolsters. Additionally, when the car is operated on marginally serviceable track, excessive oscillatory rocking motion of the car body could cause derailment of the car. Thus, it is necessary to limit and very closely control the magnitude of the relative rocking motion between the truck and the car body bolsters.
The prior art discloses a variety of side bearing structures interposed between the truck and car bolsters to limit or control relative motion therebetween; i.e., U.S. Pat. Nos. 3,400,669 and 3,713,710 both show side bearings mounted on a truck bolster which abutably engage bearing plates depending from an associated car body bolster. As illustrated in U.S. Pat. No. 3,400,669, typically the depending bearing plate structures shown in the prior art are coupled to the upwardly and outwardly sloping bottom webs or plates of the car body bolster by rivets or similar fastening means which extend through the bearing plate support structure and the bolster web at an angle substantially perpendicular to the webs. While this structure clearly couples the bearing plates to the webs, experience has shown that vertical oscillatory impacts of the associated side bearings on the bearing plates develops shearing forces acting on the rivets. These shearing forces tend to bend and ultimately stretch the rivets after extended rail operations. Thus the integrity of the coupling between each bearing plate structure and the bolster web is destroyed and the critical clearance between the bearing plate and its associated side bearing which controls the magnitude of the relative rocking motion therebetween is obviated.